The present disclosure relates to semiconductor devices in which bumps are formed on electrode portions by ball mounting methods, and which has a semiconductor substrate, and methods of manufacturing such semiconductor devices, and more particularly to semiconductor devices capable of positioning a ball near the center of an electrode portion by a reflow process and having reliable connection, and methods of manufacturing such semiconductor devices.
In recent years, there has been a need to package semiconductor components with high density, such as a resin sealing type semiconductor device, in order to deal with miniaturization of electronic devices, and to meet this need, semiconductor components have been miniaturized. In order to achieve the miniaturization, arrangement of bumps at a finer pitch have been developed, and there has been a demand for having a structure of electrode portions on which bumps are precisely formed at the centers of the electrode portions so that the bumps do not contact one another, and having semiconductor devices having such a structure.
A conventional semiconductor device in which a bump is formed on an electrode portion will be described hereinafter.
FIGS. 10A-10D shows a structure of the electrode portion in the conventional semiconductor device in detail.
FIG. 10A shows a plan view of the electrode portion, and FIG. 10B shows a cross-sectional view taken along cross sectional line Xb in FIG. 10A. An electrode pad 102 is formed on a semiconductor substrate 101 in which a semiconductor circuit is formed. A protective film 103 is formed so as to cover the semiconductor substrate 101, and has an opening through which the electrode pad 102 is exposed. A metal film 104 is formed as a barrier metal on the electrode pad 102. The metal film 104 is generally made of Ni and/or Au. The metal film 104 is formed to have a thickness equal to or larger than the thickness of protective film 103. For example, if the thickness of the protective film 103 is about 1 μm, the thickness of the metal film 104 is about 2 to 3 μm.
FIG. 10C shows a plan view of the electrode portion after a bump is formed, and FIG. 10D shows a cross-sectional view taken along cross sectional line Xd in FIG. 10C. Next, a method of the conventional semiconductor device will be described.
FIGS. 11A-11E and FIGS. 12A-12D show the method of the conventional semiconductor device in detail.
First, as shown in FIG. 11A, the electrode pad 102 is formed on the semiconductor substrate 101 in which the semiconductor circuit is formed. Then, as shown in FIG. 11B, the protective film 103 is formed so as to cover the semiconductor substrate 101, and as shown in FIG. 11C, an etching process and etc. is performed with respect to the protective film 103, thereby forming the opening so that the electrode pad 102 is exposed therethrough. Then, as shown in FIG. 11D, the metal film 104 is formed as a barrier metal on the electrode pad 102. An electroless plating method is generally used for forming the metal film 104, and the metal film 104 is made of Ni and/or Au. The metal film 104 is formed to have a thickness equal to or larger than the thickness of protective film 103. For example, if the thickness of the protective film 103 is about 1 μm, the thickness of the metal film 104 is about 2 to 3 μm. Next, as shown in FIG. 11E, a flux 105 is formed on the metal film 104. The flux 105 is formed because there is an advantage that the flux 105 serves as an adhesive for bonding the metal film 104 to the solder ball 106, and in addition, there is also an advantage that the flux 105 can remove an oxide film formed on the surface of the solder ball 106. Then, as shown in FIG. 12A, the solder ball 106 is mounted on the flux 105. FIG. 12B is a plan view of the electrode portion on which the solder ball is mounted (FIG. 12A is a cross-sectional view taken along cross sectional line XIIa in FIG. 12B). Finally, as shown in FIG. 12C, a reflow process is performed by a heat treatment, thereby centering the solder ball 106, the shape of the solder ball 106 is adjusted, and the flux 105 is removed by cleaning or the like to form a bump 107. FIG. 12D is a plan view of the electrode portion after the reflow process (FIG. 12C is a cross-sectional view taken along cross sectional line XIIc in FIG. 12D).